Graduate Students

Michael Henehan

After finishing an M/Sci in Palaeontology and Evolution at Bristol in 2009, I moved to the National Oceanography Centre, Southampton to begin a PhD with Dr. Gavin Foster, Prof. Paul Wilson and Prof. Jonathan Erez of the Hebrew University of Jerusalem. The main focus of my current research is calibrating the boron isotope-pH proxy in planktic forams. The boron isotope-pH proxy has great potential for estimating past levels of atmospheric CO2, but, like many proxies, there are a number of complications that must be considered when applying it to biogenic carbonates. So called "vital effects" may bias the recorded signal, such that the measured boron isotope ratio of a foraminiferan shell may actually reflect not only the environmental conditions around the organism, but also some imprint of the life processes of the organism. For us to gain any meaningful understanding of past CO2 levels from boron isotopes, it is vital that we understand to what degree our CO2 reconstructions may be affected by these biological interferences, and factor these out. To begin to circumvent these issues, I am constructing a range of species specific δ11B-pH calibrations for modern planktonic foraminifera (from cultures, tows and core-tops), that may be applied with confidence to the geological record of the last few million years. But by modelling the observed boron isotope signals of these foraminifera, and how they change with differing metabolic processes in the various species of modern foraminifera, I hope to reach a point where stable oxygen and carbon isotope signals in now-extinct species may be used to predict the magnitude of boron isotope "vital effects". Aside from my work on planktic foraminifera, I am also working on calibrating boron isotope-pH relationships in inorganic carbonate precipitates, scleractinian corals, and coccolithophores."